[Magnesium and cardiac function]

Free magnesium ion (Mg(2 + )) is involved in numerous processes of cardiac function. However, mechanism of regulation by Mg(2 + ) has not been fully understood. Extracellular Mg(2 + ) can act on the external surface of the cell membrane, whereas intracellular Mg(2 + ) can exert its effects via many different sites : various enzymes, intracellular organella and internal surface of the cell membrane. In this article, we will briefly review the extracellular and intracellular effects of Mg(2 + ) on each step of E-C coupling of cardiac myocytes, in an attempt to integrate them into cardiac function.